Volumetric three-dimensional printing methods

Abstract

A method for printing a three-dimensional object in a volume of a photopolymerizable liquid by photopolymerization, the method comprising: (a) providing a digital representation of a three-dimensional object that has been sliced into a plurality of sequential two-dimensional image slices along the z-direction; (b) processing each of the two-dimensional slices of the three-dimensional object into a sequence of subsampled images, each subsampled image comprising an arrangement of pixels wherein each pixel has defined x and y dimensions; (c) sequentially exposing each of the sequence of subsampled images of a slice at a selected location along the z-direction in the volume using excitation light until the volume at the selected location along the z-direction has been exposed to all of the subsampled images of the slice, and (d) sequentially repeating step (c) for a previously unexposed sequential slice of the three-dimensional object, each at different selected location along the z-direction, until the three-dimensional object is formed. A pixel can comprise a single pixel or a grouping of pixels. Preferably the pixels in a grouping of pixels are adjacent pixels. Preferably, the pixels of a subsampled image are separated from each other by a distance. Other methods are further disclosed.

The invention claimed is: 
     
         1 . A method for printing a three-dimensional object in a volume of a photopolymerizable liquid by photopolymerization, the method comprising:
 (a) providing a digital representation of a three-dimensional object that has been sliced into a plurality of sequential two-dimensional image slices along the z-direction;   (b) processing each of the two-dimensional slices of the three-dimensional object into a sequence of subsampled images, each subsampled image comprising an arrangement of superpixels, wherein each superpixel has defined x and y dimensions and comprises a grouping of a number of adjacent pixels in which the number of pixels in each of the x and y dimensions is at least 2;   (c) sequentially exposing each of the sequence of subsampled images of a slice at a selected location along the z-direction in the volume using excitation light until the volume at the selected location along the z-direction has been exposed to all of the subsampled images of the slice; and   (d) sequentially repeating step (c) for a previously unexposed sequential slice of the three-dimensional object, each at different selected location along the z-direction, until the three-dimensional object is formed.   
     
     
         2 . The method of  claim 1  wherein power density of the excitation light is adjusted to account for absorption of the excitation light in the volume in the x,y-direction and/or the z-direction before projection of a first subsampled image of a subsequent slice is initiated. 
     
     
         3 . The method of  claim 1  wherein step (a) comprises providing a digital representation of the three-dimensional object, scaling the digital representation of the three-dimensional object in the x, y, and z dimensions to a selected size, and slicing the scaled digital representation of the three-dimensional object into a plurality of sequential two-dimensional image slices along the z-direction. 
     
     
         4 . The method of  claim 1  wherein a superpixel has an arbitrary shape. 
     
     
         5 . The method of  claim 1  wherein a superpixel has a selected geometric shape. 
     
     
         6 . The method of  claim 1  wherein less than 10% of the superpixels of a slice are active at once. 
     
     
         7 . The method of  claim 1  wherein all superpixels of a subsampled image are projected simultaneously. 
     
     
         8 . The method of  claim 1  wherein each of the superpixels of a subsampled image is separated from any other superpixel of the subsampled image by a distance. 
     
     
         9 . The method of  claim 1  wherein each of the superpixels of a subsampled image is separated from any other superpixel of the subsampled image by a distance that-is at least the width of a single pixel. 
     
     
         10 . The method of  claim 1  wherein exposing the sequence of subsampled images of the slice is repeated to further expose the photopolymerizable liquid for curing. 
     
     
         11 . The method of  claim 1  wherein a slice of the three-dimensional object is not fully cured during the initial sequence of projecting the subsampled images thereof. 
     
     
         12 . The method of  claim 1  further comprising repeating step (c) one or more times to fully cure the slice. 
     
     
         13 . The method of  claim 1  wherein the photopolymerizable liquid is cured by two-photon absorption. 
     
     
         14 . The method of  claim 1  wherein step (a) comprises providing a digital representation of the three-dimensional object, adjusting the digital representation of the three-dimensional object to scale the z dimension to account for index refraction in the photopolymerizable liquid, and slicing the adjusted digital representation of the three-dimensional object into a plurality of sequential two-dimensional image slices along the z-direction. 
     
     
         15 . The method of  claim 14  further comprising scaling the digital representation of the three-dimensional object in the x, y, and z dimensions to a selected size before adjusting the digital representation of the three-dimensional object to scale the z dimension to account for the index of refraction of the photopolymerizable liquid. 
     
     
         16 . The method of  claim 1  wherein the superpixels of a subsampled image are arranged in a grid. 
     
     
         17 . The method of  claim 16  wherein the grid of a subsampled image is the same as the grid of the previously formed slice. 
     
     
         18 . The method of  claim 16  wherein the grid of a subsampled image is shifted by a selected distance in relation to that of the previously printed subsampled image to create an offset between the two subsampled images. 
     
     
         19 . The method of  claim 16  wherein the grid of a subsampled image is different from the grid of the previously formed slice. 
     
     
         20 . The method of  claim 19  wherein the grid of the subsampled image is shifted by a selected distance in relation to that of the previously printed subsampled image to create an offset between the two subsampled images. 
     
     
         21 . The method of  claim 1  wherein a subsampled image of the sequence of subsampled images of a given slice is offset by one or more pixels from the previously exposed subsampled image. 
     
     
         22 . The method of  claim 21  wherein the offset is by one pixel from the previously exposed subsampled image. 
     
     
         23 . A method for printing a three-dimensional object in a volume of a photopolymerizable liquid by photopolymerization, the method comprising:
 (a) providing a digital representation of a three-dimensional object that has been sliced into a plurality of sequential two-dimensional image slices along the z-direction;   (b) processing each of the two-dimensional slices of the three-dimensional object into a sequence of subsampled images, each subsampled image comprising an arrangement of superpixels wherein each superpixel has defined x and y dimensions and comprises a grouping of a number of adjacent pixels in which the number of pixels in each of the x and y directions is the same and is at least 2;   (c) sequentially exposing each of the sequence of subsampled images of a slice at a selected location along the z-direction in the volume using excitation light until the volume at the selected location along the z-direction has been exposed to all of the subsampled images of the slice; and   (d) sequentially repeating step (c) for a previously unexposed sequential slice of the three-dimensional object, each at different selected location along the z-direction, until the three-dimensional object is formed.   
     
     
         24 . The method of  claim 23  wherein the photopolymerizable liquid is cured by two-photon absorption.